Tasar Silk Research Articles

Development of Random Amplified Polymorphic DNA Markers for Tropical Tasar Silkworm Antheraea mylitta

Antheraea mylitta (Drury) is a tropical tasar-silk producing insect. Its populations occupying different ecological and geographical regions show a certain degree of phenotypic variability, for which they are known as “eco-races.” The eco-races are exploited for tasar silk production, and they are classified on the basis of their geographical distribution and morphology, which is often misleading when their systematic position is considered. To understand the genetic variability among the different eco-races, we used the random amplified polymorphic DNA (RAPD) method. Eighty random decamer primers were taken for RAPD amplifications. In total, 415 reproducible bands were used to generate a distance matrix, and for the subsequent clustering with unweighted pair-group method with arithmetic average. The number of polymorphic bands detected by each primer ranged from 5 to 24, with a mean value of 14.1 per primer. Percentage polymorphism was 81.9, and genetic distance values ranged from a minimum of 0.0108 between Modal and Nalia eco-races to a maximum of 0.0244 between Modal and Andhra local. The RAPD profiles obtained using A14, BC07, and C17 primers substantially differentiate all 10 commercially important eco-races, and the phylogenetic tree obtained from the data closely follows their geographical separations.

Development of Random Amplified Polymorphic DNA Markers for Tropical Tasar Silkworm <I>Antheraea mylitta</I>

Antheraea mylitta (Drury) is a tropical tasar-silk producing insect. Its populations occupying different ecological and geographical regions show a certain degree of phenotypic variability, for which they are known as "eco-races." The eco-races are exploited for tasar silk production, and they are classified on the basis of their geographical distribution and morphology, which is often misleading when their systematic position is considered. To understand the genetic variability among the different eco-races, we used the random amplified polymorphic DNA (RAPD) method. Eighty random decamer primers were taken for RAPD amplifications. In total, 415 reproducible bands were used to generate a distance matrix, and for the subsequent clustering with unweighted pair-group method with arithmetic average. The number of polymorphic bands detected by each primer ranged from 5 to 24, with a mean value of 14.1 per primer. Percentage polymorphism was 81.9, and genetic distance values ranged from a minimum of 0.0108 between Modal and Nalia eco-races to a maximum of 0.0244 between Modal and Andhra local. The RAPD profiles obtained using A14, BC07, and C17 primers substantially differentiate all 10 commercially important eco-races, and the phylogenetic tree obtained from the data closely follows their geographical separations.

Tensile and twist failure of mulberry and tasar silk

This article investigates the tensile and twist failure of mulberry and tasar silk filaments. The mulberry and tasar filaments were subjected to uniaxial loading on Instron tensile tester at different rates of extension and gauge lengths. Furthermore, the number of turns to rupture the silk filaments was tested using a twist tester. The results showed that the mulberry filament has a higher tensile and twist strength than the tasar filament. The SEM photomicrographs of the region of fracture divulged that the tensile and twist failure of mulberry and tasar filaments takes place in catastrophic and non-catastrophic modes, respectively.

Distributions of Natural Broken Filament Length for Tasar Silks

This article presents the distributions of natural broken filament length for tropical and temperate tasar silks. The results show that the tropical tasar silk displays higher mean, standard deviation, and coefficient of variation than that of temperate tasar silk. For tropical tasar silk, gamma distribution gives the best fit of natural broken filament length, whereas for temperate tasar lognormal distribution is found to give a better fit of the data of natural broken filament length.

Litterfall, litter decomposition and nutrient dynamics in a subtropical natural oak forest and managed plantation in northeastern India

In northeastern India, subtropical forests are over-exploited for timber, fuel wood and common agricultural practice like shifting cultivation, which are responsible for the degradation of natural forest. In degraded areas, large-scale plantations of different species of Quercus have been raised since 1980 for the production of economic Tasar silk. Conversion of natural forest into plantation affects the process of nutrient cycling due to management practices. Thus, it would be of importance to study the litterfall, litter decomposition process and the factors regulating the rate of litter decay in these ecosystems to improve recommendations for their management and conservation. We recorded litterfall by using litter traps and decomposition of leaf litter by nylon net bag technique to understand the amount of organic matter and nutrient return and their release in soils of forest and plantation in Manipur, northeast India. Total litterfall was 419.9 g m −2 year −1 in plantation and 547.7 g m −2 year −1 in forest. Litter decomposition rate was faster at plantation site than the forest in the early stage of litter decomposition whereas the reverse was observed at later stages of decomposition. Stepwise regression analysis showed the significant role of relative humidity and mean temperature on mass loss rates in the forest. Relative humidity, maximum temperature, population of fungi and actinomycetes were the best predictor variables for mass loss rates in plantation. Nutrient retranslocation efficiency and the immobilization of N and P in forest litter were higher than plantation. This suggests that Q. serrata growing in natural ecosystem in oligotrophic condition adapted strong nutrient conservation mechanisms to compete with the other plant species for the meager soil nutrients. The same species in plantation loses these adaptive capabilities because of exogenous supply of nutrients and in the absence of intense competition with other plant species. Thus, the optimization of organic and chemical fertilizer input in plantation is recommended for maintaining the soil fertility level to produce quality leaf for silkworm by conserving essential nutrients in the system.

Molecular Identification of Tropical Tasar Silkworm (Antheraea mylitta) Ecoraces with RAPD and SCAR Markers

The tropical tasar silkworm, Antheraea mylitta, has several ecoraces, 10 of which are commercially exploited for the production of tasar silk. These ecoraces are identified by morphological markers that are greatly influenced by photoperiod, humidity, altitude, and host plants. The DNA markers, random amplification of polymorphic DNA (RAPD), and sequence-characterized amplified region (SCAR) are identified to complement the existing morphological markers. Seven RAPD bands are selected that identify 8 of the 10 ecoraces. These identified RAPD fragments are sequenced and primers are designed for SCAR markers. Of the seven sets of primers, a single primer pair produced polymorphic SCAR bands that diagnose 5 of the 10 ecoraces. All 10 ecoraces are identified by the use of RAPD and SCAR markers together.

Repetitive DNA in tropical tasar silkworm Antheraea mylitta

Antheraea mylitta is an endemic insect species producing the world famous tasar silk. Its populations occupying different ecological and geographical regions show certain degree of phenotypic variability for which they are known as ‘eco-races’. In order to understand the genetic variability and phylogenetic relationship among the different eco-races we characterized a repetitive TaqI genomic DNA fragment as a genetic marker. The sequence analysis and Southern hybridization show the repetitive nature of TaqI DNA fragment, designated as A. mylitta TaqI family repeat, AmTFR. The PCR amplification of AmTFR reveals its presence in all the tested eco-races of tasar silkworm and some other silk producing insects. The AmTFR is evenly distributed in all 31 meiotic metaphase I chromosomes as observed by fluorescent in situ hybridization. The AmTFR based phylogenetic analysis of the eco-races is not congruent with the morphological variations and their geographical distribution.

Study of creep, stress relaxation, and inverse relaxation in mulberry (Bombyx mori) and tasar (Antheraea mylitta) silk

AbstractThe phenomena of creep, stress relaxation, and inverse relaxation/stress recovery were observed for mulberry and tasar silk. Instantaneous extension and secondary creep are both higher for tasar than for mulberry. The magnitude of inverse relaxation increases with the increase in peak tension and reduction in retraction for both varieties of silk. The extent of inverse relaxation was found to reduce because of cycling stressing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3077–3084, 2006

Enzymological characterization of pineapple extract for potential application in oak tasar (Antheraea proylei J.) silk cocoon cooking and reeling

Proteinases have the potential to effect partial solubilization of the proteinaceous gum sericin involved in binding the silk strands together in cocoon, an essential step in the silk cocoon cooking and reeling. Therefore, pineapple extract rich in cysteine proteinases was enzymologically characterized for its potential application in oak tasar ( Antheraea proylei J.) silk cocoon cooking and reeling. Optimum sodium carbonate concentration (9.8 mM) and optimum temperature (60oC) for the proteinase activity were determined. Though relatively thermostable, an enhanced activity loss was observed when the extract was incubated in the temperature range 70-90oC with sodium carbonate. Bulk of the activity (80-83%) remained after 1 hr of time-dependent inactivation at 60oC. The tasar cocoon extract neither caused inhibition of the activity nor enhanced its time-dependent loss by incubation at 60oC. However, it caused an enhanced time-dependent loss of the activity by incubation at 60oC with sodium carbonate. Considering these enzymological characteristics, experimental cocoon-cooking media were constituted by taking the pineapple extract with or without sodium carbonate at room temperature or 60oC. The results of the cocoon cooking and subsequent single silk filament reeling indicated for an applicability of pineapple extract as an effective agent for the oak tasar cocoon cooking and reeling.

Enzymological characterization of pineapple extract for potential application in oak tasar (Antheraea proylei J.) silk cocoon cooking and reeling

Proteinases have the potential to effect partial solubilization of the proteinaceous gum sericin involved in binding the silk strands together in cocoon, an essential step in the silk cocoon cooking and reeling. Therefore, pineapple extract rich in cysteine proteinases was enzymologically characterized for its potential application in oak tasar ( Antheraea proylei J.) silk cocoon cooking and reeling. Optimum sodium carbonate concentration (9.8 mM) and optimum temperature (60ºC) for the proteinase activity were determined. Though relatively thermostable, an enhanced activity loss was observed when the extract was incubated in the temperature range 70-90ºC with sodium carbonate. Bulk of the activity (80-83%) remained after 1 hr of time-dependent inactivation at 60ºC. The tasar cocoon extract neither caused inhibition of the activity nor enhanced its time-dependent loss by incubation at 60ºC. However, it caused an enhanced time-dependent loss of the activity by incubation at 60ºC with sodium carbonate. Considering these enzymological characteristics, experimental cocoon-cooking media were constituted by taking the pineapple extract with or without sodium carbonate at room temperature or 60ºC. The results of the cocoon cooking and subsequent single silk filament reeling indicated for an applicability of pineapple extract as an effective agent for the oak tasar cocoon cooking and reeling.

Effect of mating duration on oviposition rate and hatchability of the Indian tasar silk moth Antheraea mylitta (Saturniidae) in different seasons

Effect of mating duration on oviposition rate and hatchability of the Indian tasar silk moth Antheraea mylitta (Saturniidae) in different seasons

Biodegradation of chemical constituents in tasar silk cocoons after infection with fungi

Cocoons can become heavily contaminated by a large number of fungi during storage. Infection of tasar cocoons by six fungi isolated from naturally contaminated cocoons, viz. Fusarium moniliforme, Aspergillus flavus, Penicillium citrinum, Curvularia lunata, Drechslera spiciferum and Botryodiplodia theobromae exhibited a considerable loss in total, buffer-soluble protein and phenol content of the cocoons at different intervals. In all cases, maximum reduction of proteins and phenol was observed due to F. moniliforme at the end of incubation period.

Colleterectomy and its impact on some reproductive behaviour of the tropical Tasar silk moth,Antheraea mylittaDrury (Lepidoptera: Saturniidae)

Summary Morphometry of the colleterial gland and its removal (colleterectomy) were made to observe its effect on egg laying and hatching behaviour in the female Tasar silk moth, Antheraea mylitta D. during three study season. The paired colleterial gland, which is divided into two distinct regions, was found to be attached at the terminal part of a common oviduct and secretes an adhesive substance which pastes the eggs to the substratum during oviposition. Colleterectomy of the female Tasar moth just after mating and thereby removal of the gluing material induced the deposition of loose white eggs and enhanced egg laying capacity and hatching efficiency followed by a shorter incubation period without any adverse effect on the progeny. No marked changes were observed in hatching initiation and duration. Further the overall pattern of egg laying was observed continuously for 3 consecutive days in each brood of control females, while the total egg hatchability was recorded for 3 consecutive days in the first...

A new method of detection of pebrine disease in tasar silk moth, Antheraea mylitta Drury (Saturniidae)

A new method of detection of pebrine disease in tasar silk moth, Antheraea mylitta Drury (Saturniidae)

A Modified Approach to the Reeling of Tropical Tasar Silk with Adhesives

A Modified Approach to the Reeling of Tropical Tasar Silk with Adhesives

Effect of refrigeration of hatching of eggs of the tasar silk moth Antheraea mylitta Drury (Saturniidae)

Effect of refrigeration of hatching of eggs of the tasar silk moth Antheraea mylitta Drury (Saturniidae)

Community forestry for revitalising rural ecosystems: A case study

A case study focusing on the socio-economic and ecological aspects of a forest-based village, Debrasai, in the Singhbhum District of Bihar, India was undertaken in 1980 to evolve village-specific community forestry package programmes that could bring stability to the village both economically as well as ecologically. The village extending over 365.07 ha is inhabited by 361 people comprising 195 males and 166 females in 81 households. The villagers are by and large dependent on agriculture and forestry for their livelihood. The largest proportion of the land in the village is under agriculture whereas forests, in a highly degraded state, occupy only 5.7% of the total area. The villagers exploit the protected forests in their vicinity removing nearly 350.9 mt of fuelwood, 22.8 mt of small timber and 393.4 mt of fodder annually. The village has a manpower potential of 40 035 man days a year. Agriculture is the main source of employment at the moment absorbing 14 266 man days. The non-agricultural sector provides employment to an extent of 4433 man days. Fresh employment opportunities are needed to absorb nearly 53% of man days of the village at present unused. Three land-resource, skill-based package programmes, a tasar silk culture, an energy plantation, and dairying have been suggested to generate employment opportunities and to meet the basic needs of the villagers. About 115 ha of the hitherto neglected land resource has been located in the village to sustain such community forestry (CF) programmes. Tasar culture suggested on 35 ha will alone generate employment to an extent of 18 690 man days from the fourth year of tasar silk plantation. A plantation, to provide energy and fodder, on 25 and 30 ha respectively is expected to yield fuelwood, timber and fodder to more than satisfy village needs. A dairy has been recommended as it will generate income, provide nutrition and promote gobar gas production — an alternative energy source to fuelwood. The cost—benefit analysis of these projects indicates their economic feasibility with the cost likely to be recovered in 4.5 years. Debrasai being an agricultural village, a land-inequity compensatory scheme has been suggested for CF project net benefit sharing, ensuring reasonable benefit flows to the landless and marginal farmers.

Investigation of the Fine Structure and Morphology of Preswollen Indian Silk Fibers

Mulberry and tasar silk fibers were treated with formic acid, lithium thiocyanate, and zinc chloride. The fine structure of these preswollen fibers was investigated using infrared spectroscopy, x-ray diffraction, and sonic velocity. Densities were determined by means of a liquid density gradient column, and the sonic velocity was measured using a dynamic modulus tester. The surface morphology of swollen fibers was studied using electron microscopy. The x-ray and infrared crystallinity indices of fibers change due to swelling treatments, and these changes correlate to the changes in density and sonic velocity.

The Indian Tasar Silk Industry and the New Technology

The Indian Tasar Silk Industry and the New Technology

Effect of Nitrogen Plasma on the Morphology and Allied Textile Properties of Tasar Silk Fibers and Fabrics

The effect of nitrogen plasma on the morphology and properties of tasar silk fibers and fabrics has been investigated. The changes in the morphological structure were studied using the techniques of transmission electron microscopy, scanning electron microscopy, x-ray diffraction, and infrared spectroscopy. The changes in some textile properties. such as wettability, drying rate, and crease recovery, as a result of plasma treatment, were also studied. It was found that the plasma treatment is effective only on the surface of the fibers and fabrics. Wettability increased and the drying rate became faster due to the treatment; however, the crease-recovery angle decreased. The results were used to arrive at an understanding regarding the internal structure of tasar silk.